Some embodiments described herein relate generally to methods and apparatus for optical quadrature amplitude modulation (QAM) signal generation. In particular, but not by way of limitation, some embodiments described herein relate to methods and apparatus for low-loss reconfigurable optical QAM signal generation.
With a growing demand of optical communication systems with high data rates capability, optical quadrature amplitude modulation (QAM) signals are generated to provide high data-carrying capacity and high spectral efficiency. Higher-order QAM signals are currently generated by using electronic circuits to drive in-phase and quadrature (IQ) optical modulators. These approaches, however, present challenges such as the need for expensive digital-to-analog converters (DAC), high modulation loss of a typical IQ modulator, inefficient use of the non-linear region of the modulator transfer function, and a lack of reconfigurability of the QAM signals.
Accordingly, a need exists for improved and simplified methods and apparatus to achieve low-loss reconfigurable optical QAM signal generation.